Knives and scalpels used in ophthalmic surgery have small, extremely sharp blades. During eye surgery it is desirable to make the incisions as small as possible to allow for faster healing and to obviate the need for stitching the incision closed after surgery has been completed.
Surgical instruments are typically arranged by a surgical assistant and passed to the surgeon as needed. When the surgeon is finished using a particular instrument, it is customary for the surgeon to pass the instrument back to the assistant who then retains it for further use or, if use is completed, disposes of the instrument.
Operating in as confined a surgical field as the eye requires dexterity, concentration and, often, the use of microscopes or other magnifying devices to allow the surgeon to more clearly visualize the eye tissue. A constant concern during surgical procedures is the accidental cutting of either the surgeon or the assistant by an exposed cutting blade. Accidental cutting may cause serious injury and will also require that the person cut be regloved before surgery can continue.
It is known to provide scalpels and knives with blade covers or blade guards to protect the blade itself prior to surgery and to protect the blade users during surgery. Examples of such blade guards are found in the prior art.
U.S. Pat. No. 7,022,128 (Morawsky) teaches and describes a surgical knife safety handle having a blade guard that can be extended from and retracted into the handle.
U.S. Pat. No. D496,730 (Morawsky et al) teaches and describes an ornamental design for surgical knife safety handle corresponding to the knife described and claimed in the '128 patent.
U.S. Pat. No. 6,626,925 (Newman et al) teaches and describes a shielded surgical scalpel having an extendable and retractable blade guard.
A common drawback to the designs shown in the aforementioned references is the necessity for the surgeon to maintain either an uncomfortable hand position during retraction and extension of the guard, or the need for the surgeon to grip the knife in a first position to operate the blade guard, then change grips, or “walk the handle” to use the knife to make incisions. Repositioning the surgeon's hand after retracting the guard often means that the surgeon's attention and concentration is diverted from the operating field to the knife itself.
It is good surgical procedure to have the guard in place when the knife is passed back and forth between the assistant and the surgeon. Prior knife designs tend to require the surgeon's hand to be repositioned to extend the guard after the surgeon's use of the knife is completed before passing the knife back to the surgical assistant.
Commonly, the assistant already has the next instrument to be used in one hand ready to pass to the surgeon, while receiving the used instrument in the other hand. It would be awkward and dangerous for the surgical assistant to take a knife with the guard retracted and use a single hand to extend the guard before disposing of the knife.
Prior art safety handle designs thus make the extension and retraction of the guard awkward and uncomfortable by requiring repositioning of the user's hand to extend and retract the guard.
The present invention provides a safety knife with a knife blade guard that can be extended to protect the blade and retracted to expose the blade with limited repositioning of the user's hand. When the guard is extended, the blade is simultaneously retracted so that no portion of the blade extends past the guard. When the guard is retracted, the blade is extended to its full operative position.
The present invention also provides a safety knife designed to allow the movement of both the guard and blade with a single actuator.
The present design also provides a guard which allows the blade to be fully observed when the guard is in the extended position and the blade is in the retracted position.
The present invention also provides a safety knife which is economical to manufacture and simple to use.
While the following describes a preferred embodiment or embodiments of the present invention, it is to be understood that this description is made by way of example only and is not intended to limit the scope of the present invention. It is expected that alterations and further modifications, as well as other and further applications of the principles of the present invention will occur to others skilled in the art to which the invention relates and, while differing from the foregoing, remain within the spirit and scope of the invention as herein described and claimed. Where means-plus-function clauses are used in the claims such language is intended to cover the structures described herein as performing the recited functions and not only structural equivalents but equivalent structures as well. For the purposes of the present disclosure, two structures that perform the same function within an environment described above may be equivalent structures.